Can anyone explain this meditation experience pls?

I recently did a two week mindfulness retreat (with focus on Primnordial Awareness) with beautiful conditions and I was grateful to have achieved a degree of concentration, which led to a few meditation experiences. I'm a little bit unclear about this one. Please may someone suggest either a text or a book to explain this please? What occurred: I used the gap between breaths to go into the groundless ground. Experienced it as vibrations. Saw multiple white circles of lights. Then Tibetan Tankha type shapes. Then had the circle of light at the centre of my forehead swivel (like it was a stage set). Had the sense that my vision was turning around to look inwards. Saw the shapes of my eyes and cavernous holes instead of my eyeballs. This lasted for 2 seconds. Then the phenomenon faded, and I felt a snake like spiral of energy go down from my third eye. Then it was back to 'normal'. If anyone has any explanations, or has had similar experiences, and knows what it means for my practice, I'd be v grateful. With metta.